Separating and grading apparatus



Sept. 16, i930. F H QPKlNsQN 1,776,225

SEPRATING AND GRADING APPARATUS i .Xg/2%@ Mars@ Sept. 16, 1930. F.HoPKjlNsoN 1,775,225

SEPRTING AND GRADING APPARATUS Filed Nov. 3, 1928 2 Shasta-Sheet 2 54%///Zfw Patented Sept. 16, 1930 UNrran stares FRANKV -IOIPKlNSGN, OFLONDON, ENGLAND SEPARATING AND GRADING APPARATUS Application filedNovember 3, 1928. Serial No. 317,033.

This invention relates to improvements in the separation or grading ofsolid materials by the action of an air blast.

In apparatus of this character thel material 5 to be separated is fedupon a reciprocating support through which a blast of air is passed. Thelighter constituents of the material are carried upward by the air blastinto a large collecting chamber, While the heaver constituents arecaused by the reciprocating movement of the support to move along thelatter. The greater part of the lighter constituents carried upward bythe air blast fall out of the air current in the collecting chamber andare trapped in suitable poclets, but it is impossible to ensure that allof the finest particles are deposited, and, in order to avoid nuisance,the air blast is not permited to escape to the atmosphere but is kept incirculation through the apparatus. To this end 4the collecting chamberhas a duct extending across its upper part and this duct is connectedwith the intake of the fan which creates the air blast, so that the airis withdrawn from the chamber through the duct and returned to thechamber through the reciprocatingsupport.

It has been found that the ducts of apparatus of this character betweenthe chambers and the fan require frequent cleansing' or repair, in whichcase it becomes necessary to temporarily discontinue the return of theair stream to the fan and to allow the air blast to escape from theupper portion of the lchambers and to permitthe fan to take in fresh airfrom the atmosphere. While the return of the air stream to the fan isdiscontinued the chambers act as baffles which hinder the discharge ofthe spent blast from the upper part 0 of the chamber and not only causeback pressure but also vcause deflections of the air current which stirup the deposited dust and carry it into the atmosphere.

The diliiculty just referred to is overcome by the present invention byproviding the portion of the duct which is located within the collectingchamber with movable portions which may be moved into such position thatthey afford a vertical passage through the duct for free traverse of airduring the period that thereturn of the air stream to the fan isdiscontinued.

The air duct may be constructed in a form of a box-like channel havingopposite walls, preferably top and bottom walls, hinged to 50 the otherwalls and made in one or more parts in the form of flaps. The hingedflaps may be operated in any suitable manner, for instance by chains,and devices Amay be provided whereby the flaps may be locked in any "f'desired position, so that one or more may remain more or less open.

To preventthe re-entrainment by the air. stream of any dust which mayhave set- I tled in the said box-like channel, the inven- "D tionprovides a number of baffles spaced at intervals throughout the entirelength of the boX. The battles may, if desired, be fixed to `the bottomclosure members at right angles thereto andin staggered relationship toone 70 another.

Suitable arrangements are made in the inlet duct to the fanV for closingthis against the return air stream and adjustable arrangements are alsoprovided whereby the fan can 75 obtain fresh supplies of air from theatmosphere when-the return duct is inoperative.

The accompanying drawings illustrate one construction of apparatusembodying the present invention, Fig. l being a vertical longitudinalsection of the apparatus; Fig. 2 a transverse section on line 2-2 ofFig. l; Fig. 3 an enlarged view of the air duct shown in Fig. 2;and'Fig. 4 a sectionalV plan view of a section of the air duct shown inFig. 3. o

' In these drawings, a is the suction fan, b the collecting or expansionchamber, o the separating table for receiving material containing dust,CZ the relatively narrow passage leading from the separating table tothe expansion chamber, e dust pockets at either side of this passage, fconveying screws for withdrawing the dust collectedin these pockets, gbaffles which may or may not be provided within the expansion chamber toreduce the cross sectional area of this chamber locally, and z' thecover over the open top of the expansion chamber.

The foregoing parts constitute a wello known form of apparatus. 10

According to the present invention, that part of the air duct leadingfrom the expansion chamber Z) to the suction fan chamber y' which lieswithin the expansion chamber and is indicated at Z, is formed withhinged walls or flaps which can be opened or closed to any desiredextent for the purposes hereinafter specied. v

As shown in the drawings, the bottom of the air duct Z is constituted bytwo flaps m hinged to the side walls Z0 of the duct, while the top ofthe duct is constituted by two similarly hinged flaps n. 'Ihese flapsare operable as by means of chains, so that they can be opened or closedto any desired extent. For example, as shown in Fig. 3 with respect tothe top flaps n, each flap may be separately raised as by a chain o fromthe closed position shown in dotted lines in Fig. 3, so that they can beopened partially as shown in that gure, or completely so that the flapsa lie in the same plane as the side walls Z of the air duct. Or theflaps can be operated in pairs by means of a single chain p, as shown inFig. 3 with reterence to the bottom flaps m.

In the normal working position the bottom flaps m are closed, as shownin dot-ted lines in Figs. 2 and 3, and the upper iaps n are openedeither wholly or partially, so that the stream of air passing upwardsfrom the expansion chamber changes its direction in passing into the airduct Z through its upper opening.

With the bottom flaps m opened wholly or partly, as shown in full linesin Figs. 2 and 3, and the top flaps closed as shown in dotted lines inthese figures, the air which enters the duct Z from below cannot escapeto the atmosphere, but passes along the duct to the downtake g leadingto the fan chamber y' and a circulation of air is maintained. Thiscirculation can be varied to a greater or less extent by means of aclosure device such as a series of louvres 1' operable by means ofsuitable gear and adapted to close the inlet end ot' the downtake gcompletely or partially.

With the bottom and top flaps both completely opened so that they lie inthe plane of the side walls Z0, the air escapes freely from theexpansion chamber Z; to the atmosphere with minimum resistance.

With the bottom and top flaps both partly opened, part of the air willreturn to the fan and part escape directly to the atmosphere from theexpansion chamber, the proportion being determined by the extent towhich the fiaps are opened and being further determin-v able byregulation of the louvres 1'.

When the louvres 7 are completely closed against the return of the airstream from the duct Z to the fan chamber y', the fan can obtain asupply of air direct from the atmosphere by opening to any desiredextent a regulating shutter or shutters s provided in a wall of the fanchamber j. v

When the flaps of the air duct` Z are in the position for normalworking, it is desirable that dust carried by the air into or previouslydeposited from the air within the duct Z, should be arrested or itsre-entrainment in the air prevented, and this is effected by providingtransverse baffles within the duct. As shown in the drawings, thesebaiiles are constituted by plates t (see Figs. 3 and 4) extending inopposite directions inwardly from the lower flaps m and relativelystaggered, so that the air in its passage through the duct Z isconstrained to follow aI tortuous course changing direction repeatedly,with the result that dust carried by it tends to be arrested by thebaiiies t and deposited on the floor of the duct, and any dust alreadydeposited therein is not swept away and re-entrained by a high velocit-ystream of air in the duct.

The dust collected in the duct Z may be removed by opening the flaps mto discharge the accumulated dust into the dust ducts e from which it isremoved by screw conveyors f, the aps or baliies g being then turnedinwardly so as to deliect the dust from falling into tho passage CZ, andfor this and other purposes the flaps g may be made extensible asindicated in Fig. 2. Alternatively, a displaceable lid or lids may beprovided for the top of the passage d.

The material containing dust may be received from any source anddelivered upon the separating table c, the heavier dust will collect inthe chamber Z), while the lighter dust will circulate.

Having thus fully described the nature of the said inventionv and thebest means I know of carrying the same into practical effect, I claim yl. In apparatus of the kind referred to, a dust collecting chamber opento the atmosphere at its upper part, a duct extending across the chamberand adapted toreceive air from the chamber, means for introducing ablast of air into the chamber, and removing the spent blast through saidduct, said duct having movable portions adapted when Icpoved to open avertical passage through the uct.

2. In apparatus of the kind referred to, a dust collecting chamber, anair-return duct extending across said chamber, pivoted fiaps forming thevtop of said duct, pivoted iaps forming the bottom of said duct andmeans whereby the said iaps can be opened and closed. y

3. In the apparatus claimed in claim l, transverse baliies in the duct.

4. In apparatus of the kind referred to, a dust collecting chamber, anair-return duct extending across said chamber, pivoted flaps forming thetop of said duct, pivoted flaps forming the bottom of said duct, meanswhereby the said flaps can be opened and closed and transverse bafflesin the said duct.

5. In the apparatus claimed in claim 1,

balle plates Within tlie duct extending in opposite directions from theWalls of the duct iii staggered relationship.

"J. In apparatus of the kind referred to, a dust-collecting' chamber, anair-return duct extending across said chamber, pivoted flaps forming'the top of said duct, pivoted flaps forming the bottom of said duet,means Wliereby tlie said flaps can be opened and 1G closed and baffleplates Within the said duct extending in opposite directions inwardlyfrom the Walls of the duct in staggered relationsliip.

7. Apparatus of the kind referred to, coinprising a dust Collectingchamber, dust pockets formed in the bottoni of the 'said chamber, meansfor removing dust from the said pockets, an air-return duct extendingacross tlie said chamber, means for disoliarging dust from the bottom ofsaid duet and baliies in the said Chamber adapted to be turned into tliepath of' dust falling from the said duct whereby suoli dust is guidedinto the said pockets.

In testimony whereof Iy have signed my naine to this specification.

FRANK iioPKiNsoN. [L Sg

